Characterization of Thermal Desorption from Hydrogen-Carbon Co-Deposition Layers for Fusion Applications via Crystal Microbalance Measurements with Gallium Orthophosphate Crystals

Abstract

The selection of materials for plasma facing components will be a vital design decision in the construction of next-generation plasma fusion experiments. Currently, carbon is one candidate for various components of some devices. Carbon sputtering and co-deposition with hydrogen isotopes has been observed in various tokamaks during experimental runs. This will be problematic in devices running deuterium-tritium plasmas, as tritium retention is undesirable and must be controlled. This investigation intends to test the ability to remove hydrogen isotopes from co-deposition layers of carbon via thermal desorption and to characterize such desorption. Mass measurements will be made with a modified quartz crystal microbalance (QCM) setup using GaP O4 crystals and external heaters. An RGA will be used to characterize desorbed substances. The setup of the experimental apparatus will be described, along with the experimental procedure. Results confirm qualitatively that it may be possible to degas hydrogenic fuel from carbon deposition layers in future fusion devices and that such a technique is promising for future research.